Helium is way too expensive to be wasting on welding anything other than heavy aluminum parts. Any ferrous metal you can weld almost any thickness with maybe 150-175 amps, it's going to be multiple passes no matter how much power you have.
I like a 50/50 Ar/He mix for heads, blocks and intakes. Straight He just seems to have crappy arc behavior.
MIG is for production, it's just a different process, no need for condescension. MIG takes plenty of skill to do it properly, a**clowns with a MIG gun have caused more "parts failure" than we'll ever know.
60+% of welding success is prep work. The most valuable welder's tool is probably his grinder. S/F....Ken M